Update Server List from Amazon VPC

#!/bin/bash

aws ec2 describe-instances --query 'Reservations[*].Instances[*].[PublicIpAddress]' --output text --profile nash >> mainusa.txt

while true

do

aws ec2 describe-instances --query 'Reservations[*].Instances[*].[PublicIpAddress]' --output text --profile nash >> freshusa.txt

diff -Naur mainusa.txt freshusa.txt > my.patch

check=$(cat my.patch | wc -l)

echo $check

if [ "$check" -gt 0 ]

then

patch mainusa.txt < my.patch

else

echo "no chnage"

fi

rm -fr freshusa.txt my.patch

sleep 30

done